Every year, over 6000 healthy individuals undergo live donor nephrectomy in the United States to benefit a loved one, or even a stranger, with ESRD. With a stagnant deceased donor pool, live donation is a critical component of addressing the growing waiting list, and currently comprises about 40% of kidney transplants. Live kidney donors do not expect to gain any medical benefit from kidney donation; however, they do expect the medical community to understand the risks of kidney donation. Although the immediate risks to the donor are low and well-understood, long-term risks remain concerning and elusive. This is particularly true for African American (AA) donors, in whom risks of hypertension (HTN), chronic kidney disease (CKD), end-stage renal disease (ESRD), and death are highest. For example, we have shown that risk of ESRD in AA donors is 3.3x Caucasian donors and 3.1x matched healthy AA non-donors (JAMA 2014), and that risk of death in AA donors is 2.9x Caucasian donors (JAMA 2010). However, the underlying reasons for these differences remain unclear. Healthcare utilization is a major driver of health outcomes of the general population. Kidney donors are a unique population of otherwise healthy individuals who are at increased risk of poor health outcomes. Donors that do not regularly utilize primary healthcare resources including routine visits to primary care providers and nephrologists may be missing important screening and preventive measures. Failure to identify and or treat early signs of diseases, such as HTN and CKD, is likely to allow further disease progression. To better understand the relationship between healthcare utilization and race with the development of HTN and kidney disease in live donors, we will leverage a major, ongoing, R01-funded, multicenter study to address the following aims: (1) to determine the relationship between healthcare utilization following live donation and development of HTN and CKD; and (2) to investigate race-based effect modification in the relationships between health care utilization and post-donation sequelae. These aims are highly feasible given the rich primary data collection and secondary data linkage of the parent study. We hypothesize that donors with less frequent healthcare visits, particularly African American donors, will have elevated rates of post-donation HTN and CKD. Understanding the relationship between healthcare utilization and post-donation sequelae will improve donor selection, informed consent, and management. Our findings are critical to the development of robust and evidence-based post-donation clinical guidelines. Live kidney donors, who risk their safety to help others to overcome serious illness, deserve a better understanding of risk assessment and post-donation care. Our findings will have a major, direct impact on the practice of live kidney donation in the US, with a goal of ultimately influencing policy and healthcare access systems for live kidney donors to ensure optimal health outcomes.